The subject matter described herein relates generally to wind turbines, and more specifically, to methods and apparatus for use in monitoring a tachometer in a wind turbine.
Wind turbine generators utilize wind energy to produce electrical power. Wind turbine generators typically include a rotor having multiple blades that transform wind energy into rotational motion of a drive shaft, which in turn is utilized to drive an electrical generator to produce electrical power. Each of the multiple blades may be pitched to increase or decrease the rotational speed of the rotor. A power output of a wind turbine generator increases with wind speed until the wind speed reaches a rated wind speed for the turbine. At and above the rated wind speed, the wind turbine generator operates at a rated power.
Variable speed operation of the wind turbine generator facilitates enhanced capture of energy by the wind turbine generator when compared to a constant speed operation of the wind turbine generator. However, variable speed operation of the wind turbine generator produces electricity having varying voltage and/or frequency. More specifically, the frequency of the electricity generated by the variable speed wind turbine generator is proportional to the speed of rotation of the rotor. A power converter may be coupled between the electric generator and an electrical grid. The power converter outputs electricity having a fixed voltage and frequency for delivery on the electrical grid. Additionally, the power converter relies on a tachometer for rotor position feedback and will impose torque disturbances on the turbine if there is an error in the tachometer signal.